1. Field of the Invention
The present invention generally relates to rigs adapted to support well construction and work-over operations. More particularly, the present invention relates to self-erecting rigs. In another aspect, the present invention relates to self-erecting rigs having modular structures configured to support and house well equipment.
2. Description of the Related Art
Cost effective production of oil or gas reserves requires, in part, surface support and control systems that economically deploy drilling and completion systems and methods. Prior art drilling rigs have inherent drawbacks that reduce the cost effectiveness of utilizing drilling and completion systems to construct new wells and work over existing wells. While the drawbacks discussed below are in reference to an offshore platform, these drawbacks may also be found in other situations.
First, well operations utilizing prior art rigs tend to occupy a significant amount of deck space. Typically, floating platforms are massive structures that are designed to withstand decades of service in a harsh ocean environment. Despite the enormous overall size of these offshore platforms, the deck on a given offshore platform can become crowded with various well equipment. Because the lack of deck space may limit options in operation sequencing or selection of equipment, it is usually desirable to minimize the amount of equipment on the platform deck. Prior art rigs are deployed in conjunction with mud tanks, power packs, mud pumps, blow-out preventer accumulators, and other equipment. This equipment is usually located adjacent to the prior art rig. Thus, the rig and related equipment have a relatively large xe2x80x9cfootprintxe2x80x9d that reduces the amount of available deck space.
Also, the erection of prior art rigs and related equipment can be time consuming and effort intensive. Prior art rigs and related equipment are usually assembled piece by piece at the offshore facility. This operation usually requires up to hundreds of individual xe2x80x9clifts.xe2x80x9d That is, each piece of equipment must be lifted and handled a number of times before final installation. Further, while an offshore platform may have dedicated cranes for general uses, a xe2x80x9cleapfrogxe2x80x9d crane is usually required to lift and handle the bulky components of the prior art rig and related equipment. Thus, construction of prior art rigs reduces the overall cost effectiveness of well activities. The present invention overcomes these and other drawbacks of the prior art.
A preferred embodiment of the present invention includes a rig adapted for deployment on a platform and includes hydraulic jacks and rails. The rig structure includes stacked modules incorporating a self-latching mechanism to interlock adjacent modules. The modules include open areas within their structure for storing well equipment such as mud pumps, mud tanks, and power packs. This equipment is pre-fitted into the modular structures before shipment to the offshore facility. The rails are disposed on a platform and guide the modules to the hydraulic jacks. Hydraulic jacks, also fixed onto the platform, are configured to releasably engage and elevate the modules.
During deployment, a first module is placed onto the rails and trolleyed to the hydraulic jacks. The jacks, when actuated, engage the first module and hoist it to a pre-determined height. A second module is then slid below the first module. The jacks then lower the first module onto the second module. As the first module seats on the second module, the self-latching mechanism locks the two modules together. Thereafter, the jacks release the first module, return to their initial position, engage the second module, and hoist the first and second modules. A third module is slid below the first and second module, and the process repeats.